1. Field of the Invention
This invention relates generally to paper making machinery and more particularly to an improved radial diffuser having insert rings for providing microturbulence to a receiving fluid stock suspension and uniformly discharging the same fluid stock suspension into circumferential discharge tubes disposed around the outside of the radial diffuser for feeding the inlets of a forming unit.
2. Description of Related Art
Competition and the constant demand to improve paper quality especially cross-direction (CD) basis weight profile has made many existing paper, board, tissue machine inlet distribution systems obsolete. Market volatility has forced many manufacturers to produce other new products on machines once exclusively reserved for the production of one or two established products.
New multi-product machine requirements have severely tasked the existing inlet stock flow distribution system on these existing machines. The flow rate process requirement of these machines make them unable to meet current market product quality standards.
A paper making machine has a paper fluid stock suspension that typically gets supplied to multiple inlets of a head box under conditions of uniform velocity and pressure for maximum uniformity of paper sheet formation. Various types of paper stock flow distributors have been used, but a common problem exists of not achieving equal distribution of the stock flow from the flow distributor multiple outlets to the inlets of the headbox.
For example, in U.S. Pat. No. 3,296,066, issued Nov. 13, 1963 to M. S. Green et al., a stock flow distributor is described comprising a header having an inlet end and the opposite end of the header is closed by a closure plate with a smooth inner surface extending normal to the axis of the header. The header is provided with multiple outlets in the side wall comprising short lengths of pipe, each of which is connected to an inlet pipe of the headbox. The entering flow of paper stock to the flow divider head has its velocity substantially extinguished by impingement against the closing plates, and this stock is then distributed among all the outlets and the lines leading to the headbox. However, experience with this distributor has shown that this flow distributor does not produce a stable jet of fluid into the sidewall outlets.
In U.S. Pat. No. 3,563,852, issued Feb. 16, 1971 to Walter E. Rojeski, a flow divider is described which is similar to the one disclosed in Green et al. U.S. Pat. No. 3,296,066.
The flow divider includes a generally cylindrical housing which has an axially extending inlet connected to the pump and a series of circumferentially spaced radially extending outlet tubes which are connected to a corresponding inlet tube on the body of a headbox. The housing includes an upper peripheral flange on which is mounted a semi-spherical or dome-shaped cover having a base flange secured to the flange by a series of bolts. A resilient thin rubber membrane or diaphragm is clamped between the flanges so that it is positioned adjacent the outlet tubes and normal to the stock flow. Air is supplied to the cover above the diaphragm. The air pressure supplied above the diaphragm is substantially equal to the stock pressure in the line from a pump so that the diaphragm is normally maintained in the generally flat position and deflects when a pulse is received. However, experience with the flow divider has shown that the stock flow to the outlet tubes is not uniform by not having a consistent pressure at each outlet tube.
A radial-flow distributor is described in a product description paper distributed by PAMA PAPIERMASCHINEN GmbH of Freiberg, Germany referred to as PAMA Information No. 1. The PAMA radial-flow distributor is described as providing an even distribution of a volume flow in a radial direction due to an exactly vertically directed flow on a polished circular impact plate. The radial-flow distributor achieves a wider range variety by changing the volume flow and consistency without negatively effecting the cross profile. It does not cause a separation of the suspension contents due to different density (i.e. no separation of fibers and ash). To ensure an undisturbed flow, the flow passage is described as being six-to-ten fold of the pipe diameter. The radially distributed volume flow is fed to the inlet chamber of a headbox by pipes and hoses. However, this radial-flow distributor does not have means for deflocking of stock suspension travelling through a section passage.